C-Minus—The Fallout of Parents' Smoking

Children who live with smokers may need more oranges and other rich sources of vitamin C, a new study concludes. It finds that exposure to even a little secondhand smoke significantly depresses concentrations of this important vitamin.

Although the body makes a host of antioxidants to quash free radicals and other oxidants, one of the most effective antioxidants is vitamin C, a nutrient that must be derived from the diet or supplements.

Throughout the past dozen years, data have been accumulating to show how oxidants from cigarette smoke and other sources can damage the lungs and other tissues. Indeed, overexposure to oxidants, which are biologically damaging molecular fragments, has been linked to the development of many cancers, heart disorders, lung diseases, and even degenerative conditions typically attributed to aging.

Not surprisingly, research has shown that smokers use up their antioxidants–including any vitamin C–at accelerated rates. Researchers at the University of Puerto Rico worried whether the vitamin C loss witnessed in smokers might also develop in children who live with them, inhaling their secondhand smoke. So, they compared vitamin C consumption and blood concentrations of this nutrient in 512 children 2 to 12 years old. Half the youngsters had at least one smoking parent.

In the January American Journal of Clinical Nutrition, the researchers now report finding evidence that secondhand smoke diminishes the vitamin C circulating in the blood of children.

Ventilation and diet may help

For their new study, Alan M. Preston and his colleagues recruited children from low-income barrio families visiting a pediatric center affiliated with the university. The researchers collected information on the children's diets and whether their parents smoked cigarettes. Preston's group also measured cotinine, a nicotine-breakdown product, in urine samples from each child and vitamin C concentrations in blood samples.

In general, these children were healthy, and their blood tests showed acceptable concentrations of vitamin C. However, those with at least one smoking parent had lower vitamin C concentrations than the others did.

The cotinine measurements revealed that even kids with smoking parents had sustained low nicotine exposures compared with those seen in other groups of people who regularly encounter secondhand smoke. He attributes this to ample year-round ventilation of homes in the San Juan area. "People mainly live with open windows and fans blowing. So, [indoor] smoke is really low," Preston says. In colder climes, he observes, especially in winter, "you'd have closed rooms and people smoking in cars with closed windows, so that kids would get a pretty good dose of smoke."

Despite the modest smoke exposures, however, his team found significant smoke-related reductions in circulating vitamin C. "In our study, the effect we see in kids exposed to just a little [secondhand] smoke is about one-quarter of that vitamin C reduction in smoking adults," Preston says. Among smokers, studies have measured a 20 percent or so reduction in blood concentrations of this antioxidant.

On average, youngsters from homes with smoking parents had 94 percent the concentration of the vitamin that those from nonsmoking homes had. The exposed kids still had plenty of the antioxidant. Indeed, he notes, "if you're taking plenty of vitamin C, which most of our kids did, you can offset the losses due to cigarette smoke." However, the biochemist cautions, in children with "marginal" consumption of the vitamin, "even a minimal reduction in circulating vitamin C could compromise their antioxidant protection."

The bottom line, Preston says, is that smoking parents should be especially diligent in making sure their children get ample vitamin C–either from dietary sources or daily supplements.